The goal of the proposed research is to identify effective gastric cancer prevention programs that improve cancer outcomes, reduce disparities, and enhance the cost-effectiveness of gastric cancer prevention in the U.S. This will be accomplished by constructing a flexible decision-analytic simulation model of gastric cancer capable of estimating the contribution of risk factor patterns on gastric cancer trends and assessing the costs, benefits, and cost-effectiveness of primary (smoking cessation) and secondary (surveillance) prevention strategies. As several factors are changing the landscape of gastric cancer control, including a better understanding of the disease natural history, role of risk factors on disease progression, and new noninvasive endoscopic technology to detect and treat precancerous and cancerous lesions, this model will synthesize available clinical, epidemiologic, and economic data to project long-term outcomes and guide clinical study design. Our specific aims are: (1) to develop a natural history model of gastric cancer, including the role of risk factors on disease progression. This model will be empirically calibrated using U.S. epidemiologic data on age-specific prevalence and incidence of precancerous lesions and cancer; (2) to estimate the decline in gastric cancer incidence attributable to declining prevalence of H. pylori, smoking, and other risk factors. Using a population-based model of gastric cancer we will incorporate data on risk factor trends to forecast gastric cancer incidence and mortality; (3) to assess the cost-effectiveness of technology-based surveillance and treatment strategies for patients with precancerous lesions. We will evaluate the effectiveness of endoscopic and serology-based diagnostic and therapeutic technologies for dysplastic and asymptomatic cancerous lesions; (4) to compare the relative effectiveness of alternative gastric cancer control strategies on disparities. We will develop natural history models for specific race/ethnicity, immigrant, and other select subgroups, incorporate demographic trends, and assess the impact of prevention and treatment strategies to improve cancer outcomes and reduce disparities. In summary, this research will synthesize the best available data, improve upon an existing modeling framework, and develop a new set of analytic tools to estimate and project gastric cancer trends; establish management guidelines for patients with gastric precancerous lesions; and provide insight on the relative costs, benefits, and risks associated with different gastric cancer prevention and control strategies. My career goal is to become an independent investigator dedicated to the application of multidisciplinary, decision- analytic methods to improve cancer prevention and control policies. In conjunction with additional training in secondary data analysis, advanced decision-analytic methods, and epidemiology, the execution of this proposed mentored research in a multidisciplinary and highly-collaborative environment will provide the additional experience, knowledge, and skills needed to successfully transition to research independence.